Effects of easy-to-use protein-rich energy bar on energy balance, physical activity and performance during 8 days of sustained physical exertion

Energy Deficit and Factors Associated with Energy Balance during a Combat Deployment in U.S. Army Special Operation Forces Soldiers

The purpose of this study was to determine the difference between estimated energy expenditure (EE) and self-reported dietary intake (EI), and factors associated with energy balance in deployed U.S. Army Special Operations Forces (SOF) Soldiers.

METHODS

Forty-six SOF Soldiers (age: 30.1 ± 3.5 yrs, body mass index: 27.7 ± 4.1 kg/m2) completed surveys on demographic data, mission activity characteristics, gastrointestinal issues, ration consumption, resilience, mood state, and dietary intake using a 127-question food frequency questionnaire at the end of a six-month deployment. EE was estimated using a SOF-specific prediction equation with a physical activity factor of 2.1. A paired t-test compared reported energy intake (EI) with estimated energy expenditure (EE). Pearson correlations identified significant variables associated with energy balance, which were then incorporated into a multiple linear regression model. The regression analysis included Profile of Mood States (POMS) anger and POMS depression as predictor variables to determine their influence on energy balance.

RESULTS

Reported mean EI was 2512 ± 1059 kcal·d-1, while estimated mean EE was 5272 ± 525 kcal·d-1. The mean energy imbalance was -2854 kcal/d (95% CI: -2655 to -3055, p < 0.001), with all participants in negative energy balance (range: -492 to -3813 kcal/d). POMS depression (r = 0.517, p < 0.01) and POMS anger (r = 0.363, p = 0.020) were associated with energy balance. The regression model was significant (R2 = 0.23, F (2, 38) = 7.02, p < 0.01), with POMS depression significantly predicting energy balance (β = 50.76, p = 0.011).

CONCLUSIONS

Deployed SOF Soldiers reported high EE and limited EI, which may negatively impact performance. Higher POMS depression scores were associated with lower energy deficits. Future studies should investigate the relationship between mood and energy balance, using direct measures of EI and EE.

Performance nutrition for cold-weather military operations

.High daily energy expenditure without compensatory increases in energy intake results in severe energy deficits during cold-weather military operations. The severity of energy deficits has been proportionally linked to declines in body mass, negative protein balance, suppression of androgen hormones, increases in systemic inflammation and degraded physical performance. Food availability does not appear to be the predominant factor causing energy deficits; providing additional rations or supplement snack bars does not reduce the severity of the energy deficits. Nutrition interventions that allow greater energy intake could be effective for reducing energy deficits during cold-weather military operations. One potential intervention is to increase energy density (i.e. energy per unit mass of food) by increasing dietary fat. Our laboratory recently reported that self-selected higher energy intakes and reductions in energy deficits were primarily driven by fat intake (r = 0.891, r² = 0.475), which, of the three macronutrients. Further, soldiers who ate more fat lost less body mass, had lower inflammation, and maintained net protein balance compared to those who ate less fat. These data suggest that consuming high-fat energy-dense foods may be a viable nutritional intervention that mitigates the negative physiological effects of energy deficit and sustains physical performance during cold-weather military operations.

Use of accelerometers and inertial measurement units to quantify movement of tactical athletes: A systematic review

The dynamic work environments of tactical athletes are difficult to replicate in a laboratory. Accelerometers and inertial measurement units provide a way to characterize movement in the field. This systematic review identified how accelerometers and inertial measurement units are currently being used to quantify movement patterns of tactical athletes. Seven research and military databases were searched, producing 26,228 potential articles with 78 articles included in this review. The articles studied military personnel (73.1%), firefighters (19.2%), paramedics (3.8%), and law enforcement officers (3.8%). Accelerometers were the most used type of sensor, and physical activity was the primarily reported outcome variable. Seventy of the studies had fair or poor quality. Research on firefighters, emergency medical services, and law enforcement officers was limited. Future research should strive to make quantified movement data more accessible and user-friendly for non-research personnel, thereby prompting increased use in tactical athlete groups, especially first responder agencies.

An Alternate Approach to Military Rations for Optimal Health and Performance

INTRODUCTION

Operational ration packs are the sole source of nutrition when military personnel cannot access fresh food and field kitchens due to deployment and training in remote and hostile locations. They should be light, durable, nutrient rich, and contain sufficient energy to ensure that the personnel can carry out the expected duties. The macronutrient composition of rations has remained relatively unchanged despite escalating concerns related to the health and operational readiness of personnel globally. Currently, the New Zealand Defence Force (NZDF) provides the personnel with a 24-hour ration pack. The aims of this study were to (1) analyse the nutrient content, cost, and weight of the NZDF-supplied ration pack and (2) develop and analyse an alternate ration pack. The alternate ration pack was designed with the intention of improving overall quality and macronutrient distribution ratio, to align with optimal health and performance outcomes.

MATERIALS AND METHODS

Nutrient and weight analyses of the NZDF and alternate ration packs were conducted using nutrition analysis software Foodworks V. 10 (Xyris software). The ration packs were costed using information from the NZDF and from commercial online shopping websites (particularly Countdown supermarket and an online shop, iHerb). Data from nutrition panels were entered into Foodworks V. 10 (Xyris software). The data underlying this article will be shared on reasonable request to the corresponding author.

RESULTS

The NZDF-supplied ration pack cost 37.00 NZD and contained an excessive amount of sugar (636 g or 46% total energy) and marginally insufficient protein (118.7 g or 9% total energy) to sustain physically active military personnel. Comparatively, the alternate ration pack was more costly (63.55 NZD) and contained significantly less sugar (74.6 g or 7.2% total energy) and exceeded protein (263.1 g or 26% total energy) requirements for physically active military personnel. Furthermore, the alternate ration pack was significantly lighter (0.71 kg) than the NZDF ration pack (1.4 kg). In summary, the alternate ration was nutritionally superior and lighter when compared to the currently supplied NZDF ration, but more expensive when purchased as a one-off.

CONCLUSIONS

This work highlights the shortcomings of currently supplied military rations packs (i.e., excessive sugar and marginally inadequate protein) and proposes a novel alternate approach to ration pack formulation. This approach would significantly reduce sugar and increase protein and fat content in military rations. Although this work indicates that the alternate approach (which would produce lighter and nutritionally superior rations) is more costly, this cost could be reduced significantly through bulk purchasing and purpose-built rations and food items. Considering these findings, field user-testing of the alternate ration pack is recommended and subsequent reformulation of guidelines for ration pack development, as appropriate.

Effects of Acute Heat and Cold Exposures at Rest or during Exercise on Subsequent Energy Intake: A Systematic Review and Meta-Analysis

The objective of this meta-analysis was to assess the effect of acute heat/cold exposure on subsequent energy intake (EI) in adults. We searched the following sources for publications on this topic: PubMed, Ovid Medline, Science Direct and SPORTDiscus. The eligibility criteria for study selection were: randomized controlled trials performed in adults (169 men and 30 women; 20–52 years old) comparing EI at one or more meals taken ad libitum, during and/or after exposure to heat/cold and thermoneutral conditions. One of several exercise sessions could be realized before or during thermal exposures. Two of the thirteen studies included examined the effect of heat (one during exercise and one during exercise and at rest), eight investigated the effect of cold (six during exercise and two at rest), and three the effect of both heat and cold (two during exercise and one at rest). The meta-analysis revealed a small increase in EI in cold conditions (g = 0.44; p = 0.019) and a small decrease in hot conditions (g = −0.39, p = 0.022) for exposure during both rest and exercise. Exposures to heat and cold altered EI in opposite ways, with heat decreasing EI and cold increasing it. The effect of exercise remains unclear.

Negative energy balance during military training: The role of contextual limitations

During multiday training exercises, soldiers almost systematically face a moderate-to-large energy deficit, affecting their body mass and composition and potentially their physical and cognitive performance. Such energy deficits are explained by their inability to increase their energy intake during these highly demanding periods. With the exception of certain scenarios in which rations are voluntarily undersized to maximize the constraints, the energy content of the rations are often sufficient to maintain a neutral energy balance, suggesting that other limitations are responsible for such voluntary and/or spontaneous underconsumption. In this review, the overall aim was to present an overview of the impact of military training on energy balance, a context that stands out by its summation of specific limitations that interfere with energy intake. We first explore the impact of military training on the various components of energy balance (intake and expenditure) and body mass loss. Then, the role of the dimensioning of the rations (total energy content above or below energy expenditure) on energy deficits are addressed. Finally, the potential limitations inherent to military training (training characteristics, food characteristics, timing and context of eating, and the soldiers' attitude) are discussed to identify potential strategies to spontaneously increase energy intake and thus limit the energy deficit.

Effects of energy balance on appetite and physiological mediators of appetite during strenuous physical activity: secondary analysis of a randomised crossover trial

Energy deficit is common during prolonged periods of strenuous physical activity and limited sleep, but the extent to which appetite suppression contributes is unclear. The aim of this randomised crossover study was to determine the effects of energy balance on appetite and physiological mediators of appetite during a 72-h period of high physical activity energy expenditure (about 9·6 MJ/d (2300 kcal/d)) and limited sleep designed to simulate military operations (SUSOPS). Ten men consumed an energy-balanced diet while sedentary for 1 d (REST) followed by energy-balanced (BAL) and energy-deficient (DEF) controlled diets during SUSOPS. Appetite ratings, gastric emptying time (GET) and appetite-mediating hormone concentrations were measured. Energy balance was positive during BAL (18 (sd 20) %) and negative during DEF (–43 (sd 9) %). Relative to REST, hunger, desire to eat and prospective consumption ratings were all higher during DEF (26 (sd 40) %, 56 (sd 71) %, 28 (sd 34) %, respectively) and lower during BAL (–55 (sd 25) %, −52 (sd 27) %, −54 (sd 21) %, respectively; Pcondition < 0·05). Fullness ratings did not differ from REST during DEF, but were 65 (sd 61) % higher during BAL (Pcondition < 0·05). Regression analyses predicted hunger and prospective consumption would be reduced and fullness increased if energy balance was maintained during SUSOPS, and energy deficits of ≥25 % would be required to elicit increases in appetite. Between-condition differences in GET and appetite-mediating hormones identified slowed gastric emptying, increased anorexigenic hormone concentrations and decreased fasting acylated ghrelin concentrations as potential mechanisms of appetite suppression. Findings suggest that physiological responses that suppress appetite may deter energy balance from being achieved during prolonged periods of strenuous activity and limited sleep.

Energy Deficiency in Soldiers: The Risk of the Athlete Triad and Relative Energy Deficiency in Sport Syndromes in the Military

Military personnel experience energy deficit (total energy expenditure higher than energy intake), particularly during combat training and field exercises where exercising energy expenditures are high and energy intake is reduced. Low energy availability (energy intake minus exercising energy expenditure expressed relative to fat free mass) impairs endocrine function and bone health, as recognized in female athletes as the Female Athlete Triad syndrome. More recently, the Relative Energy Deficiency in Sport (RED-S) syndrome encompasses broader health outcomes, physical and cognitive performance, non-athletes, and men. This review summarizes the evidence for the effect of low energy availability and energy deficiency in military training and operations on health and performance outcomes. Energy availability is difficult to measure in free-living individuals but doubly labeled water studies demonstrate high total energy expenditures during military training; studies that have concurrently measured energy intake, or measured body composition changes with DXA, suggest severe and/or prolonged energy deficits. Military training in energy deficit disturbs endocrine and metabolic function, menstrual function, bone health, immune function, gastrointestinal health, iron status, mood, and physical and cognitive performance. There are more data for men than women, and little evidence on the chronic effects of repeated exposures to energy deficit. Military training impairs indices of health and performance, indicative of the Triad and RED-S, but the multi-stressor environment makes it difficult to isolate the independent effects of energy deficiency. Studies supplementing with energy to attenuate the energy deficit suggest an independent effect of energy deficiency in the disturbances to metabolic, endocrine and immune function, and physical performance, but randomized controlled trials are lacking.

Nutritional Requirements for Sustaining Health and Performance During Exposure to Extreme Environments

Dietary guidelines are formulated to meet minimum nutrient requirements, which prevent deficiencies and maintain health, growth, development, and function. These guidelines can be inadequate and contribute to disrupted homeostasis, lean body mass loss, and deteriorated performance in individuals who are working long, arduous hours with limited access to food in environmentally challenging locations. Environmental extremes can elicit physiological adjustments that alone alter nutrition requirements by upregulating energy expenditure, altering substrate metabolism, and accelerating body water and muscle protein loss. The mechanisms by which the environment, including high-altitude, heat, and cold exposure, alters nutrition requirements have been studied extensively. This contemporary review discusses physiological adjustments to environmental extremes, particularly when those adjustments alter dietary requirements.

Training-induced changes in daily energy expenditure: Methodological evaluation using wrist-worn accelerometer, heart rate monitor, and doubly labeled water technique

INTRODUCTION

Wrist-mounted motion sensors can quantify the volume and intensity of physical activities, but little is known about their long-term validity. Our aim was to validate a wrist motion sensor in estimating daily energy expenditure, including any change induced by long-term participation in endurance and strength training. Supplemental heart rate monitoring during weekly exercise was also investigated.

METHODS

A 13-day doubly labeled water (DLW) measurement of total energy expenditure (TEE) was performed twice in healthy male subjects: during two last weeks of a 12-week Control period (n = 15) and during two last weeks of a 12-week combined strength and aerobic Training period (n = 13). Resting energy expenditure was estimated using two equations: one with body weight and age, and another one with fat-free mass. TEE and activity induced energy expenditure (AEE) were determined from motion sensor alone, and from motions sensor combined with heart rate monitor, the latter being worn during exercise only.

RESULTS

When body weight and age were used in the calculation of resting energy expenditure, the motion sensor data alone explained 78% and 62% of the variation in TEE assessed by DLW at the end of Control and Training periods, respectively, with a bias of +1.75 (p <.001) and +1.19 MJ/day (p = .002). When exercise heart rate data was added to the model, the combined wearable device approach explained 85% and 70% of the variation in TEE assessed by DLW with a bias of +1.89 and +1.75 MJ/day (p <.001 for both). While significant increases in TEE and AEE were detected by all methods as a result of participation in regular training, motion sensor approach underestimated the change measured by DLW: +1.13±0.66 by DLW, +0.59±0.69 (p = .004) by motion sensor, and +0.98±0.70 MJ/day by combination of motion sensor and heart rate. Use of fat-free mass in the estimation of resting energy expenditure removed the biases between the wearable device estimations and the golden standard reference method of TEE and demonstrated a training-induced increase in resting energy expenditure by +0.18±0.13 MJ/day (p <.001).

CONCLUSIONS

Wrist motion sensor combined with a heart rate monitor during exercise sessions, showed high agreement with the golden standard measurement of daily TEE and its change induced by participation in a long-term training protocol. The positive findings concerning the validity, especially the ability to follow-up the change associated with a lifestyle modification, can be considered significant because they partially determine the feasibility of wearable devices as quantifiers of health-related behavior.

Diet Macronutrient Composition, Physical Activity, and Body Composition in Soldiers During 6 Months Deployment

Introduction

Optimal diet together with good physical fitness maintains readiness and military performance during longer deployments. The purpose of this study was to describe changes in dietary macronutrient and energy intake, total physical activity and body composition during a 6-month deployment in South Lebanon. Furthermore, associations of diet macronutrient intake and physical activity on body composition were also studied.

Materials and Methods

Forty male soldiers kept a 3-day food diary and their body composition was measured via bioimpedance and ultrasonography. Total physical activity was evaluated by accelerometers in a subgroup of participants. Measurements were conducted in the PRE-, MID-, and POST-deployment.

Results

Mean carbohydrate intakes were 39.5–42.6 E%, protein intakes 18.7–22.3 E%, and fat intakes 34.9–35.7 E%. Daily energy intake remained stable (10.1–10.3 MJ/D). Total physical activity was decreased during deployment (e.g., step count from 9,835 ± 2,743 to 8,388 ± 2,875 steps/day, p = 0.007). Skeletal muscle mass and subcutaneous fat increased by 1.3% (p = 0.019) and 1.9% (p = 0.006), respectively. Energy and fat intake associated positively with body mass and skeletal muscle mass (r = 0.31–0.48, p &lt; 0.05–0.001).

Conclusions

Carbohydrate intakes and physical activity were low, compared with the general recommendations. Protein intakes were relatively high. Skeletal muscle mass and subcutaneous fat increased. Suboptimal diet together with low level of physical activity may have a negative impact on body composition, physical performance, and cardiometabolic health. Consequently, soldiers should be encouraged to consume more fiber-rich carbohydrates and less saturated fatty acids as well as maintain a high level of physical fitness to sustain military readiness during long-term deployments.

Body weight and body composition changes during military training and deployment involving the use of combat rations: a systematic literature review

Dismounted military personnel operate in physically and psychologically demanding environments, with energy intake from combat rations often falling short of their requirements, leading to reductions in body weight and changes in body composition, which can impact both their health and performance. This review systematically investigated the effects of the continual use of combat rations for periods of 3–40 d on body weight and/or body composition in military personnel engaged in training or deployment. In all, ten databases were searched from their inception until October 2016. Outcome data were described narratively, with studies assessed for quality and risk of bias. A total of thirty studies undertaken over 3–34 d were included. Studies were rated positive, neutral or negative in quality according to the Academy of Nutrition and Dietetics Quality Checklist, with many at risk of bias. Reductions in mean body weight varied, from a negligible decrease of 0·1 % during 8 d of combat training to a substantial decrease of approximately 8·3 % during 12 d of energy restriction during a US Army Ranger course. Decreases in fat mass, fat-free mass and percentage body fat were also reported. There is thus evidence that the continual use of combat rations for periods of 3–34 d results in reductions in body weight and body composition changes which, in some scenarios, may impact on the performance of troops. Body weight and composition should be routinely monitored before and after field activities, and at more regular intervals depending on the length, intensity and type of activity being undertaken.

A review of the physiological and psychological health and wellbeing of naval service personnel and the modalities used for monitoring

Naval cohorts rely heavily on personnel to ensure the efficient running of naval organisations. As such, the wellbeing of personnel is essential. In an occupational setting, naval service personnel experience a variety of physiological and psychological stressors. Most naval services arrange annual physical fitness and body composition tests to ensure the physical readiness of personnel. However, these tests only evaluate a small amount of physiological capabilities. Components such as aerobic and strength capabilities are assessed, however, other components of physical fitness such as speed, agility, anaerobic capacity and flexibility are not. In addition to the physical capabilities, personnel are impacted by fatigue, nutrition and psychological stressors such as copping in stressful situations or dealing with time away from family and friends. This review will discuss the physiological and psychological factors that affect personnel's wellbeing. In addition to this, it will also evaluate the methods that are used to assess both physiological and psychological wellbeing.

Considerations for protein supplementation in warfighters

Ingestion of dietary protein stimulates the synthesis of numerous body proteins. This effect is manifest via hyperaminoacidemia with insulin as a permissive factor. In a sedentary person in energy balance, it is possible to maintain nitrogen balance while consuming protein at an intake of 0.8 g protein · kg(-1) · d(-1). What is unclear is whether being in nitrogen balance is optimal for protein synthesis and not merely adequate and representative of adaptive strategies that could lead to accommodation in "stressed" physiological states. It is clear that being in negative energy balance results in reductions in lean mass and reduced rates of protein synthesis, which can be mitigated by consumption of higher (i.e., 2-3 times the RDA) dietary protein. That long-term practice of inadequate protein intake leads to reduced metabolic, physiological, and physical function provides the basic rationale for the consumption of more than merely adequate protein to prevent not only adaptation but accommodation. Warfighters engaged in combat have been shown to have high daily physical activity energy expenditure, engage in voluntary energy restriction, and are under high metabolic and mental stress. Thus, as a group warfighters would be at risk of consuming suboptimal protein intakes and therefore may benefit from higher amounts of dietary protein intake. Balanced against the potential risk of consuming higher protein, the scientific documentation for which is lacking, there is a strong rationale for the recommendation of higher protein intakes in warfighters who are engaged in field operations.